The present invention generally relates to a recording apparatus which is provided with a paper winding means for winding recording papers while holding end portions of the recording papers, and more particularly to a recording apparatus featuring control of transfer of the recording papers.
Generally, in the case that a plurality of recording operations are done for a single recording paper, it is necessary to repeatedly reciprocate the recording paper over a recording head. For example, in a color printer of thermal transcription, a recording paper, when thermally transcribed or transferred with four ink films, (for example, yellow, magenta, cyan and black ink films) is required to reciprocate correctly in order to prevent the transcribed image on the recording paper from being out of coincidence in colors, etc. However, in a prior art color printer of the above-described type, particularly when the recording is effected on a general recording paper in the form of a sheet without sprocket holes formed therein, it is difficult to reciprocate correctly the recording paper.
On the other hand, there is another kind of recording apparatus which performs recording while it transfers a recording paper in the forwarding direction and in the returning direction, to be employed in the case that a picture image or the like is to be recorded on the recording paper. For example, it is necessary in a color printer of thermal transcription to transfer four inks, namely, yellow, magenta, cyan and black sequentially, onto the recording paper. If sheets of recording papers smaller than a predetermined size are put in the prior art color printer of thermal transcription, however, rear ends of the recording papers are detached from a platen when the first color is transferred, and therefore the recording papers will remain in the color printer and cannot be properly discharged.
Further, in the case where the recording papers are reciprocated many times in order to record a colored picture image onto the recording papers, it is required, for example, in the color printer of thermal transcription, to record four colors onto each of the recording papers by using four transfer films of yellow, magenta, cyan and black. In such a case as above, the recording papers should be correctly reciprocated so as not to give rise to disagreement in overlapping of the colors. Also, when an X-Y plotter using a platen is employed, it is necessary to reciprocate the recording papers in such a manner as not to miss the position. It has been difficult for the X-Y plotter to correctly reciprocate the recording papers only by the rotary movement of the platen when the recording papers are normal sheets of papers without sprocket holes.
Although ways to transfer the recording papers while a part of the papers are held have been proposed, a fear remains that the recording papers might be wrinkled or deflected if they are not securely held.
As has been described above, the prior art color printer of thermal transcription performs transferring of each color, with the use of tapes applied with four thermal transcription inks, i.e., yellow, magneta, cyan and black thermal transcription inks, onto a recording paper. The compiling of these four colors will result in a desired picture image. Therefore, in such a case as described above where the thermal transcription is carried out many times on the same portion of the recording paper, the thermal transcription ink is transferred onto the recording paper in the middle of the reciprocal transfer of the recording paper.
However, when the transferring direction of the recording papers is reversed, if the thermal transcription ink transcribed immediately before the reversal is not completely fixed or dried, undesirable slipping or blurring of the transcribed image at that portion may take place.
Recording papers should not be out of position relative to a transferring means for transferring the recording papers. Moreover, in the color printer of thermal transcription or the like in which another image is overlapped onto the already-formed image for recording, both images should not be slipped or blurred relative to each other. According to the prior art recording apparatus, however, it could not be prevented that the recording papers are deflected when the transferring direction of the recording papers is reversed, and also the images to be overlapped with each other could not be correctly overlapped.
Meanwhile, general printers are designed to transfer recording papers while maintaining balance with the platen. By way of example, a guide plate is provided for balancing or a roller is placed so as to control timing of the start of transfer of the recording papers. After the recording papers are pressed into contact with this roller, they are transferred. Nevertheless, in some cases, recording papers are transferred to the platen out of balance due to the existence of difference in thickness or deflections. In such cases, not only the recorded images are inclined, but wrinkles or creases result and the recorded images are disturbed, resulting in jamming of recording papers. The jammed recording papers cannot be used again. Moreover, it is difficult and troublesome to remove the jammed recording papers. Especially in the case where a single recording paper is reciprocated many times for recording, such as in the case of the color printer of thermal transcription, etc., it is highly desirable to transfer the recording paper while maintaining strict balance of the paper with the platen.